Weather Service Report


880 
FXUS66 KPQR 200407
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
907 PM PDT TUE AUG 19 2014

.SYNOPSIS...NORTHWEST FLOW WILL CONTINUE OVER THE REGION FOR MUCH 
OF THE WEEK BRINGING A PATTERN OF MORNING CLOUDS AND AFTERNOON
SUNSHINE FOR THE INLAND AREAS AND PERSISTENT MARINE CLOUDS ALONG THE
COAST. THERE WILL ALSO BE SOME POTENTIAL FOR SOME DRIZZLE 
AT TIMES ALONG THE NORTH COAST. AN UPPER LEVEL LOW PRESSURE DROPPING
SOUTHEASTWARD ACROSS THE INLAND NORTHWEST ON FRIDAY...COULD RESULT IN
A FEW SHOWERS AND THUNDERSTORMS ACROSS THE SOUTH WASHINGTON AND NORTH
OREGON CASCADES ON FRIDAY.

&& 

.SHORT TERM...FOG PRODUCT THIS EVENING SHOWS MARINE CLOUDS ARE
BEGINNING TO PUSH UP INTO THE COAST RANGE GAPS. EXPECT AREAS OF FOG
INITIALLY...BUT AS THE MARINE LAYER DEEPENS...AREAS OF DRIZZLE WILL
BE POSSIBLE LATER TONIGHT INTO WEDNESDAY MORNING. FURTHER
INLAND...SHALLOW CUMULUS OVER THE CASCADE FOOTHILLS IS BEGINNING TO
FLATTEN INTO A STRATUS DECK BETWEEN 5-7KFT. THE NAM...WRFGFS AND GEM
MODELS ALL INDICATE THESE CLOUDS WILL FILL IN AND EXPAND WESTWARD
INTO THE WILLAMETTE VALLEY AS THE NIGHT PROGRESSES. THE SKY COVER
FORECAST WAS TRENDED TOWARDS THIS IDEA. OFTEN THE WEST SIDE OF THE
WILLAMETTE VALLEY BETWEEN HILLSBORO AND CORVALLIS CAN REMAIN CLOUD
FREE IN THIS TYPE OF PATTERN SO SKY COVER WAS TRENDED DOWN IN THIS
REGION WEDNESDAY MORNING DUE TO UNCERTAINTY. NEVERTHELESS...A 10MB
PRESSURE GRADIENT EARLIER THIS EVENING BETWEEN ASTORIA AND PENDLETON
AND CURRENT SATELLITE TRENDS SUGGEST THE CLOUDIER SOLUTIONS ARE
LOOKING MORE AND MORE LIKELY. 

MODELS LOOSELY AGREE A CLOSED LOW WILL MEANDER SOUTHEASTWARD ACROSS
THE INLAND NORTHWEST FRIDAY. DUE TO THE CLOSE PROXIMITY OF THE UPPER
LEVEL LOW PRESSURE...THERE IS CERTAINLY A CHANCE FOR SHOWERS AND
THUNDERSTORMS TO DEVELOP OVER THE CASCADES...ESPECIALLY OF SOUTH
WASHINGTON...ON FRIDAY...AND TO A LESSER EXTENT SATURDAY. EVEN THOUGH
MODEL SOUNDINGS SUGGEST THE PORTLAND METRO AREA WILL REMAIN
CAPPED...GIVEN THE MID LEVEL FLOW SHIFTS BRIEFLY TO
NORTHEASTERLY...IT IS CERTAINLY POSSIBLE ANY STORMS THAT DEVELOP OVER
THE SOUTH WASHINGTON CASCADES COULD DRIFT SOUTHWESTWARDS TOWARDS THE
EASTERN SUBURBS OF PORTLAND FRIDAY EVENING IN A PATTERN SOMEWHAT
SIMILAR TO LATE MAY 2012. WILL LET THE MID SHIFT DIGEST THE FULL
SUITE OF 00Z MODELS BEFORE FURTHER ADJUSTMENTS TO THE FORECAST ARE
MADE. 

OTHERWISE...LARGE SCALE NORTHWEST FLOW WILL CONTINUE TO DOMINATE THE
OVERALL WEATHER PATTERN INTO THE FORESEEABLE FUTURE...BRINGING
PERIODS OF MORNING CLOUDS AND AFTERNOON SUNSHINE. TEMPERATURES WILL
LIKELY HOVER A FEW DEGREES BELOW NORMAL THE NEXT COUPLE OF DAYS
BEFORE TEMPERATURES CLIMB SOLIDLY INTO THE 80S OVER THE WEEKEND FOR
THE WILLAMETTE VALLEY. /NEUMAN


.LONG TERM...FRIDAY NIGHT THROUGH MONDAY...THE GFS...ECMWF...AND 
DGEX ARE ALL IN AGREEMENT THAT A WEAK SHORTWAVE WILL PUSH THROUGH 
LATE FRIDAY NIGHT INTO SATURDAY MORNING ON THE BACK SIDE OF THE 
TROUGH OVER THE PACIFIC NORTHWEST...BUT LIMITED MOISTURE BETWEEN 
1000-500 MB AS WELL AS 1000-700 MB WILL LIMIT ANY PRECIPITATION FROM 
THIS SYSTEM TO THE NORTHERN CASCADES IN OUR AREA. AS THE TROUGH 
MOVES OFF TO THE EAST...THE PREVIOUS THREE MODELS ARE HINTING AT 
ANOTHER SHORTWAVE MOVING THROUGH ON MONDAY. BECAUSE OF HOW FAR OUT 
THIS FEATURE IS IN THE FORECAST...AND LACK OF AGREEMENT BETWEEN 
MODELS ON TIMING AND MOISTURE CONTENT...I HAVE LEFT POPS TO 
CLIMATOLOGY BUT INCREASED CLOUD COVER ALONG THE NORTH COAST. -MCCOY 


&&

.AVIATION...A BREAK IN THE MARINE STRATUS OCCURRED LATE THIS
AFTERNOON...AND MUCH OF THE NORTH OREGON AND SOUTH WASHINGTON
COAST REMAINS VFR AT CURRENT. HOWEVER IFR OR LOWER CONDITIONS HAVE
NOW PUSHED BACK INTO THE CENTRAL OREGON COAST. EXPECT MVFR/IFR
STRATUS
TO SURGE BACK INTO THE NORTHERN COASTAL LOCATIONS LATER THIS
EVENING. CONDITIONS ALSO CURRENTLY VFR IN THE INTERIOR...BUT
EXPECT THE MARINE STRATUS TO PUSH UP THE COLUMBIA OVERNIGHT.
STRATUS WILL LIKELY REACH INTO KPDX AND KTTD BY AROUND 12Z. AT
THE SAME TIME...A CLOUD DECK WILL BE FORMING ALONG THE CASCADE
FOOTHILLS AND BACK BUILDING TO THE WEST OVER THE VALLEY TAF
SITES. HOWEVER...EXPECT THIS DECK TO BE VFR AT AROUND 5000 FT. ANY
INTERIOR MVFR STRATUS SHOULD LIFT TO VFR BY 18Z. EXPECT THE
COASTAL SITES TO ALSO SEE IMPROVEMENT TO VFR AT SOME POINT
TOMORROW AFTERNOON.

KPDX AND APPROACHES...VFR IN CONTROL THIS EVENING AND MOST OF THE
OVERNIGHT PERIOD. MVFR STRATUS PUSHING UP THE COLUMBIA WILL
LIKELY REACH THE TERMINAL AROUND 12Z. CONDITIONS TO IMPROVE TO
VFR BY 17Z OR 18Z. PYLE

&&

.MARINE...CHOPPY SEAS TODAY HAVE CALMED DOWN THIS EVENING. SEAS
CURRENTLY SIT AT 5 TO 6 FT AND THE PRIMARILY SWELL PERIOD HAS
INCREASED TO ABOUT 11 SEC...UP FROM THE 7 TO 8 SEC EARLIER. WINDS
ALSO FAIRLY LIGHT...AT NW 5 TO 10 KT. DO NOT EXPECT MUCH CHANGE
IN THE PATTERN THIS WEEK AS HIGH PRESSURE REMAINS OVER THE NE
PAC...BUT SEAS WILL CONTINUE TO FLATTEN AS W-NW SWELL DECREASES
LATE WEDNESDAY THROUGH THE END OF THE WEEK. PYLE

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA    
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV    
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON 
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS 
COMMONLY REFERRED TO AS THE FORECAST AREA.

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